1. Field of the Invention
The invention concerns a fire arm equipped with an enabling system, whereby the fire arm contains a device which can prevent any firing, whereas the enabling system contains a transmitter/receiver mounted on the fire arm, a unit to be carried by the shooter containing means to send back a signal transmitted by the transmitting part of the above-mentioned transmitter/receiver to the receiving part of this transmitter/receiver, and a monitoring device to monitor the signal received by said receiving part and to control the device which can prevent any firing, whereby the latter actually prevents the firing if the monitoring device does not recognize said signal as that of an authorized shooter.
2. Discussion of the Related Art
Such an arm, which is often called an intelligent fire arm or `smart gun`, is meant to prevent its being used by a non-authorized person.
A fire arm of this type is described in U.S. Pat. No. 5,704,153. The transmitter/receiver mounted on the fire arm is a radio transmitter/receiver transmitting, for example at the moment when the grip of the fire arm is seized, a preferably coded radio signal of a specific frequency, for example in the order of 900 MHz, is sent to a transponder built-in in a ring which is worn by the shooter, which returns the signal to the first transmitter/receiver.
If the latter receives a correct and sufficiently strong signal, it will activate a solenoid which unlocks a bolt element of the firing mechanism, thus enabling the shooter to fire.
Whereas, in traditional coding systems, the distance between the transmitter of the coded signal and the receiver is of no importance, this is quite different in case of a fire arm. For it is not exceptional that a criminal filches the fire arm of an authorized person. We must in this case prevent the criminal from shooting at the authorized person with the fire arm.
The principle of the above-mentioned known fire arm and of other similar fire arms making use of electromagnetic waves as a means to identify the authorized person in this sort of situations, is that, when the fire arm is removed from the person carrying the means for sending back a signal, for example in a ring, the strength of the signal which is sent back to the receiving part of the transmitter/receiver mounted on the fire arm becomes too weak for the monitoring device to be activated.
The attenuation of the signal is not always influenced by the mere distance between the means for sending back a signal and the transmitter/receiver. It can be influenced by the direction of the antennas, the condition of the battery supplying the power to the above-mentioned means and to the transmitter/receiver, the presence of metal objects, etc.
Due to the above-mentioned influences of the direction of the antennas, of electromagnetic interference, etc. it can happen that the authorized shooter is not identified, whereas the identification means worn by him are situated at the appropriate distance from the transmitter/receiver mounted on the fire arm. Thus, the enabling system of these fire arms is not entirely reliable.